无人值守WSN中基于中国剩余定理的可靠数据生存方案

无人值守无线传感器网络(UWSN)通常部署在环境恶劣或敌对环境中,在静态汇聚节点(或基站)部署困难的情况下,感知节点无法完成感知信息的实时汇聚传输,需暂时维持感知数据的生存状态。为了增强数据生存的概率,提高感知数据的抗损坏、擦除和篡改能力,重点研究无人值守无线传感器网络中的数据加密生存问题,提出了一种基于中国剩余定理(CRT)多等级秘密共享的可靠数据生存方案。基于网络中节点的信誉模型,设计了节点权重密钥存储机制,增强了数据加密密钥分割存储的有效性,并结合基于中国剩余定理的秘密共享机制,提升了原有数据加密分发和恢复过程的效率。此外,还讨论了基于中国剩余定理的秘密共享方案具有的良好同态性质,并依此设计了子密钥组合运算方案,提高了数据加密生存方案中子密钥运算的安全性,进一步确保了数据生存方案的安全、可靠。     

无人值守无线传感器网络中可靠数据生存恢复方案

无人值守无线传感器网络( UWSN)通常部署在环境恶劣或敌对环境中,在静态汇聚节点(或基站)部署困难的情况下,感知节点无法完成感知信息的实时汇聚传输,需暂时维持感知数据的生存状态。为增强数据生存概率,提高感知数据的抗损坏、擦除和篡改能力,在建立攻击模型假设的基础上,针对失效节点攻击假设,提出一种基于中国剩余定理加密秘钥分割机制的可靠数据生存恢复方案。利用门限秘钥分割存储机制增强密钥分割存储安全性,确保数据加密分割生存的可靠性,针对恶意节点攻击所造成的不可靠数据恢复威胁,构建基于恢复不一致性的恶意恢复攻击检测方案及基于多数表决的恶意恢复攻击识别机制,确保数据恢复的安全、可靠。     

基于副本复制和Bloom Filter 的P2P 概率路由算法

非结构化P2P网络资源定位过程中的查询延迟、查准率和查询成本难以同时被优化,为此,提出一种基于副本复制和Bloom Filter技术的P2P概率路由算法DCBF(data copying and Bloom Filter).DCBF基于有向随机网络,对资源对象进行少量的复制,并将各个副本随机路由给网络中的节点;接收副本的节点,以分布式衰减Bloom Filter向邻近节点传递副本的成员资格信息.理论分析和实验结果均表明,DCBF仅需复制少量的副本,通过以分布式衰减Bloom Filter传递副本的成员资格信息,使得网络中的绝大多数节点能够感知到副本的成员资格信息,从而使得各个节点能够以极低的查询代价,在较低的路由延迟范围内,高概率地将查询路由到目标节点.     

一类新的分布式随机验证无线传感网络节点克隆攻击检测

由于无线传感器网络节点的无人值守性,攻击者很容易捕获并复制节点,利用节点的安全证书把复制节点发布到无线传感器网络的各个角落,进而秘密发动各种攻击。提出一类新的分布式节点复制攻击检测协议,协议采用随机区域单元映射和域内随机线选验证相结合的方法进行攻击检测。仿真结果显示,协议的随机验证特性使网络能量消耗均匀,延长网络的生存周期。域内线选验证使协议的通信开销和储存开销较低并具有较高的检测率。     

无线传感网中基于自适应概率广播的数据保存

对于部署在恶劣环境中且无法放置Sink节点的无线传感器网络,节点的能量有限且易于损坏.每个节点为了避免自己死亡后数据丢失,需要将数据分发到网络中其他一部分节点上进行保存.但是,由于节点只知道自己邻居的信息,同时存储容量有限,因此如何有效地进行数据分发和存储是一个具有挑战性的问题.提出一个基于自适应概率广播的数据保存协议APBDP来解决这个问题.在APBDP中,节点通过一种自适应的概率广播机制分发数据,这种机制不仅可以使所有节点接收到数据包,而且能有效地减少数据的冗余传输以节省节点能量.此外,节点利用LT码来对数据进行编码存储,所有节点完成数据的分发和存储后,数据采集者只需要访问少量的节点就能恢复出所有的源数据.理论分析和实验表明,APBDP不仅具有较高的解码性能,而且能量有效.     

断续连接移动自组网络中的数据复制

在移动自组网络中,节点的移动或是无线连接的中断会引起频繁的网络分割.因此,访问节点并获取相应的数据是相当困难的.通过理论和统计分析得到特定运动模型对应的网络分割模式,建立了网络分割模式与数据复制有效性之间的联系,推导出了理想复制方法在特定网络环境下能够获得的数据可用性的上限,也指出纯随机复制方法可提高数据可用性.基于上述分析,提出了一种新的数据复制方法RICMAN(replication in intermittently connected mobile ad hoc networks)来提高断续性连接移动自组网络的数据可用性.该方法将所需数据以副本的形式复制到一系列拓扑结构相对稳定和资源充足的特定节点上,为处于同一分区的节点提供数据服务.副本的分布和更新基于半概率性数据分发协议实现.此协议能够识别可能的跨越多个网络分区的运动节点,由这些节点传播数据及其更新,从而在断续性连接网络中最大化数据传输.为了保持副本的一致性,该方法使用一种弱一致性模型——最终一致性模型,以确保所有的更新最终在有限的延迟内传送到所有的副本处.仿真结果显示,RICMAN方法能够以较小的开销获取较高的数据可用性,经过优化后,数据可用性仅比理想上限低10%～15%.     

一类新的基于移动序贯测试的无线传感网络节点克隆攻击检测

无线传感器网络经常被部署在无人值守且严酷的环境中,攻击者能通过克隆节点来发起各种的内部攻击.本文提出一种新的分布式移动节点克隆攻击检测方法.仅当证人节点和被检测节点相遇或相关证人节点相遇时,检测信息被转发到证人节点进行检测.同时,利用序贯概率比检测技术,避免单一样本产生的高错误率.移动辅助的随机验证和序贯测试技术相结合,降低传统路由寻径开销和误警率/虚警率.仿真结果表明,协议具有较高检测效率和合理的开销.     

P2P网中基于文件分片的副本建立策略

在大规模P2P网络中,为了提高数据的可用性,可以通过在系统中多个节点上建立数据副本的方法来增加数据的冗余度.为了减小副本建立的开销,可采用一种基于文件分片的副本建立策略,将需要复制的数据文件先进行分片,然后把这些分片在一组选取好的候选节点间进行分发复制.该方法能够充分利用网络带宽,明显减小建立副本所需的时间开销.     

改进的LEACH协议在井下通信系统中的应用

无线传感器网络由能量受限的节点组成,通过部署这些节点以便收集特定监测区域内的有用信息.基于层次的LEACH协议通过将节点分簇以实现数据融合.随机选择的簇头节点接收到本簇成员的数据后进行融合处理,将结果传输到汇聚节点.避免每个节点都与远距离的汇聚节点直接通信,从而节约能耗.将无线传感器网络应用于井下通信系统,能够提高通信的安全性.LEACH的分簇结构与矿井内分坑道工作的情况相类似,把每个坑道作为一个簇,将多数传感器节点安置在坑道内的固定位置,少量节点随矿工位置移动,再将这些节点采集的数据传输至簇头节点.本文主要针对井下通信系统的特点对现有的LEACH协议进行改进,优化了簇头节点的选举方法,并允许部分节点采用多跳方式与汇聚节点通信,使其更符合矿井结构的要求,从而节约了能耗,并且有效地延长了网络的生存时间.     

无线传感器网络中基于散列链的随机密钥预分发方案

密钥管理足无线传感器网络安全机制和服务的基石,随机密钥预分发是当前最有效的密钥管理机制,但目前的随机密钥预分发方案存在一个潜在的挑战:无法同时获取理想的网络安全连通性和网络抗毁性.文中提出了一种基于散列链的随机密钥预分发方案,通过有效调节散列链长度、公共辅助节点数、散列链数量等参数,节点仅需预分发数量较少的密钥信息,就能够以较高的概率建立对偶密钥.而且,即使存在大量的受损节点仍能保持较强的网络抗毁性.理论分析和模拟实验证明了所提出方案的有效性和安全性.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.